If it takes 5 men 20hours to brick a house, how long will it take 2 men to do the job if they work at the same rate?

50 hours.

Step-by-step explanation:

To solve these type of question we should always remember that man power is inversely proportionate to the work done.

That means if we double the manpower work done will be half. and when we reduce the manpower to the half time take to complete the work will be double.

It takes 5 men to brick a house = 20 hours

so 1 man will brick the house = 20 × 5

                                                = 100 hours

Therefore, 2 men will brick the house =  

                                                               = 50 hours.

step-by-step explanation: so we look at the formula un = a + (n-1)d

un is the amount of seats

n is the nth term aka row number

a is the original sequence/row number

d is the difference between each term

so in this a=22 d=6 and n can remain as n because we are simply formjng a rule

lets put these in the equation

un=22+(n-1)(6)

this is your answer to part a

however

lets double check that this is correct, we'll try putting it into the second term

un=a+(n-1)d

u2=22+(2-1)(6)

u2=22+6

u2=28

as the question said the second row has 28 seats so now we know the formula we made is correct.

as for part b

un=a+(n-1)

its asking us to find a row with 100 seats.

remember un was the amount of seata so all we do is substitute this in.

un=100 a=22 d=6

un=a+(n-1)d

100=22+(n-1)(6)

so now we simplify to find n which is the row number.

100-22=22+(n-1)(6)-22

78=(n-1)(6)

78/6=(n-1)(6)/6

13=n-1

13+1=n-1+1

14=n

so now we know that in the 14th row there is 100 seats.

hope this and that you understood! its my first time using the app or anyone out on here : p its also me to revise so a bunch! ask more questions if you dont understand ☺